The invention relates to a throttle opening sensor which produces a signal indicative of the throttle opening of an engine.
Of the throttle opening sensors known in the prior art, a potentiometer having a resistor film is most conventional. With this potentiometer type sensor, there is a problem that a premature abrasion of the resistor film is experienced. In an electronic digital control system which is utilized to control the fuel injection, the number of revolutions of the engine or the automatic transmission, it is necessary to provide an analog-digital converter which converts an output from the potentiometer into a digital code.
If a digital code generator or rotary type is formed, the individual split electrodes must be configured to produce a binary code representing a numerical value which is proportional to the throttle opening. With this binary code, if the throttle opening includes 16 steps from 0 to 15, it is necessary to provide a corresponding binary code as indicated in table 1 below.
TABLE 1 ______________________________________ Binary Throttle Opening Code Throttle Opening Binary Code ______________________________________ 0 0000 8 1000 1 0001 9 1001 2 0010 10 1010 3 0011 11 1011 4 0100 12 1100 5 0101 13 1101 6 0110 14 1110 7 0111 15 1111 ______________________________________
At transition between the steps of the throttle opening, the output code will represent a throttle opening which includes a significant deviation from the actual throttle opening. For example, in the Table 1 given above, between the throttle openings 3 and 4, the output code of the rotary code generator may be "0000" indicating an opening "0", "0111" indicating an opening "7" or "0110" indicating an opening "6". If a code produced which deviates from the actual opening, an errorneous operation of the electronic control system may result.